Wideband (high-speed) data transfer at rates in excess of 40 Gigabits-per-second (Mbps) is expensive for dedicated bandwidth (e.g., leased lines) over the existing telecommunications infrastructure. Over modest ranges where an unobstructed line of sight exists, a laser communication link can provide an alternative means of obtaining dedicated bandwidth at high data rates.
For this and other reasons, wireless information transmission systems in general are increasingly desirable as alternatives to costly wired installations and high telecommunications rates which prevail even for short distance communications. Radio frequency communications systems have the disadvantage of requiring that carrier frequency and communications bandwidth be assigned to an application, since the much wider beamwidths and sidelobes can interfere with each other. Thus, there is an increasing need for communications systems, such as those using light frequencies, that transmit large quantities of information in a line-of-sight application without creating interference problems.
DC blocking capacitors are used in a wide variety of applications, such as in the fields of RF (radio frequency), wireless communications, high speed electronic circuits, and traditional amplifier circuits. Each of these different fields require decoupling of different circuit sections.
In one example, laser communication transmit and receive modules require broadband DC blocking capacitors. These DC blocking capacitors have to work over multi-octave bandwidths. Current manufactures produce the broad bandwidth capacitors by attaching a 0.1 uf chip cap to an 82 pf parallel plate cap. However, due to flight requirements (for example, requirements in the space industry) for plate spacing in the chip caps, their physical size often exceeds a 50 ohm line width of a substrate they are being mounted on. This creates a discontinuity on the 50 ohm line. This discontinuity limits bandwidth, causes group delay, and generates the need for matching circuitry.